mitt romney is a good debater. i am just okay. >> reporter: mitt romney began practicing in june and continued prepping tuesday. chris christie said mitt romney's performance will turn the race upside down. >> you will say we have a barn burner now. >> reporter: mitt romney's run -- paul ryan dialed back expectations. >> i don't think one event is going to make or break the campaign. >> reporter: paul ryan says mitt romney will lay out the choice voters have, especially when it comes to the economy. >>> oracle workers hear from the master tonight. he delivered the key note address. more than 50,000 people are in san francisco for the event. he described his vision of hardware and software that works together. >> oracle 12c is the foundation for an expanding business, cloud business at oracle corporation. it is the foundation, the software foundation of the oracle cloud. >> it runs through thursday. >>> a justin bieber first. on stage. what happened last night that ,,,, [ owner ] i need to expand to meet the needs o